Improvement in the manufacture of steel



UNITED STATES PATENT OFricr-O CHARLES ATTWOOD, OF TON LAW IRON WORKS,COUNTY OF DURHAM, ENGLAND.

IMPROVEMENT IN THE MANUFACTURE OF STEEL.

Specification forming part of Letters Patent No. 38,140, dated April 14,186

To all whom it may concern Be it known that I, CHARLES Arrwoon, of TonLaw Iron Works, in the county of Durham, England, have invented a newand useful Improvement in the Production or Manufacture of Steel andIron of a Steely Quality; and I hereby declare the following to be afull, clear, and exact description of the same.

My invention essentially consists in the production of steel and of ironof a quality approximate to steel, which may be called steely iron,simply by bringinginto astate of liquefaction by means of heat a mixtureof malleable iron of such kinds as in themselves are capable ofproducing good or serviceable steel and steely iron and of a certainkind or kinds of non-malleable or crude cast-iron-such, for instance, asare usually called spiegeleiscn which are also by their nature capableof being made into good and serviceable steel, in certain proportions toeach other, as hereinaf ter specified, by which mixture and liquefactionof those materials hard steel or soft steel or steely iron arerespectively produced, ac cording to the different proportions in whichsuch two several materials or ingredients may be severally employed,such proportions also requiring to be varied according to the differencein their quality in respect to the greater quantity of carbon containedin each, and to their greater or less tendency in consequence thereof tomake such steel or steely iron of harder or softer quality.

In order to more fully describe my said invention and the manner inwhich it may be most successfully practiced or employed, I will nowproceed to describe or specify the kinds and qualities of malleable ironand of crude cast-iron, respectively, which I employ in mixture, asaforesaid, and also the modes in which the operations may be carriedout.

First, as it regards such malleable iron,it is desirable that it shouldbe such as, by whatsoever method or process it may have been produced,has been as well and uniformly as may be deprived of that excess ofcarbon which is the cause of the non-malleable quality in the severalkinds of what is commonly described bythe names of pig-iron, crude iron,or cast metal, and in this respect 1 find such malleable iron as isproduced by what is called the paddling process is, if well anduniformly puddled,very suitable, although, if well and uniformlydecarbureted, any other sort or kind of malleable iron of quality inother respects as good may equally well be employed.

Secondly, as regards such crude cast metal or cast-iron as is to beemployed in such mixture, as aforesaid, I have found the kind besttitted for my purpose to be that variety of bright and white cast-ironof acrystalline and highly-lamellar structure and almost silverywhiteness, which is called in England specular iron, or by itsequivalent German name, spiegeleisen, as that iron is remarkably uniformas respects the proportion of carbon it contains, and generally ofhighly superior quality, containing a less proportion than most othersorts of the other matters or in gredients which are injurious to thequality of malleable iron or steel,respcctively, and for the fullerinformation of persons who may hereafter make use of my invention I maymention that I have not in general found any sensible difference betweengood samples of this kind of iron as made in Germany and such as hasbeen madein England, or as is or has been made in the United States ofNorth America from an ore there called franklinite. Where excellence anduniformity of quality in the steel or steely iron intended to beproduced is especially desirable I prefer to use in the working of mysaid process or invention the said specular crude iron or spiegeleisento any other kind or sort with which I am acquainted; but I have alsofound that the description of white cast metal or crude iron which iscommonly called byEnglisli ironmasters refined metal, as made from otherkinds orsort-s of either gray or white crude metal by the process whichthey call the finery process in well-known kinds of fur naces, by aid ofblast or otherwise, is for the most part pretty nearly in the samecondition in respect of the proportion of carbon contained in it as suchspecular crude iron or spiegeleisen, and, in so far as it may be inother respects of good quality for steel-making generally, may be usedin substitution for such specular iron in making steel or steely ironaccording to my process; and I have also found that besides suchspecular iron or spiegeleisen and such refined metal other sorts ofwhite crude iron in general-such as that which is frequently producedfrom ores in the blast-furnace smelting process which were not to'oimpure in other respects, and therefore unfit in its own nature forbeing converted into serviceable steel-may also be used in substitutionfor such specular crude iron or spiegeleisen, although with moredifficulty and uncertainty as to the proportion in which it should beused from its containing more varying proportions of carbon; and thereare some instances in which such white pig-iron,where very servieeably.

Crude refined metal which may have been produced by other means orprocesses than that of the refinery already mentionedas, for instance,by blowing atmospheric air or steam, or both, into or under the surfaceof molten crude iron of any kindmay, wheneverit may have beendecarbureted to near about the same degree as such other refined metal,be also used in substitution for such specular crude iron in nearlysimilar proportions and, in so far as it may be otherwise of equalquality or purity with the effect of producing steel or steely iron ofequal or nearly equal quality.

In like manner it will be found that crude white or gray metal producedby the remelting of malleable-iron scraps or other malleable iron incontact with fuelas, for instance, in cupola furnaces-or, such as may beproduced by so renielting it in contact with fuel in any other manner,may also, in so far as it may have been brought to a nearly similarstate as regards its quantity of carbon to such specular iron, be usedin substitution for it in so far as fitness in other respects for makingsteel of the required quality according to any other method may be foundto belong to it.

, Though I have have so far described my said invention in so far onlyas relates to the production of steel or steely iron by melting togetherinto one mass certain proportions of white crude or non-malleable metalof proper quality with certain proportions of malleable iron, also ofproper quality, yet I have also found that gray crude iron, whether asit comes in that state directly from the blast-furnace or as it may beproduced by any other mode, and even that the sort of gray iron which isusually called mottled iron, as being visibly composed of a mixture ofcrude gray and crude white metal, may each of them, so long as in otherrespects of a quality good enough for making serviceable steel by otherprocesses, be similarly used in substitution for such sorts of crudewhite metal in mixture with malleable iron for making steel or steelyiron according .to my process proper care being taken to use the same indue proportion to the difl'erent quantities of carbon which such gray ormottled metal may contain as compared with such sorts of white metal,but with the disadvantage, upon one hand, of being liable tosupercarbonize such steel if used in even a small excess of dueproportion, and to thereby injure or destroy its malleability, and alsowith the disadvantage, upon the other hand, of increasing somewhat thedifficulty of melting the materials from the smaller proportionatequantity in which it may sometimes or generally have to be employed, andon this account I prefer when using it to take theless rich kind of suchgray iron instead of such as iron-masters usually describe as No. I orNo. 2, but such as is more generally used in forges for puddling, andeven in some cases to take such mottled iron as containing still less ofcarbon; and I may here remark that whereas the specular white metal orspiegeleisen is sometimes found to have passed in the blast-furnace orin certain rem eltin g processes-as by remeltin g in contact with thefuel in founders cupolafurnaces-into a kind of mixed or mottled iron,this mixed or mottled iron may also be employed in similar proportions,and in general I would indicate that from six to ten parts of gray crudeiron with from ninety to ninetyfour parts of paddled malleable iron willmake a soft steel or'a steely iron, While for making hard steel as muchas from thirty to forty parts of gray crude iron and from sixty toseventy parts of malleable iron may be employed.

As regards the proportion in which white specular crude metal should beused to the malleable iron in the working of my process, I have foundthat for making soft steel or steely iron-by which last I mean a kind ofsteel partaking so far of the nature of iron as to be more or lessreadily capable of being weldedabout six or eight parts of such specularmetals to about ninety or ninety-two parts of such malleable iron may besuccessfully employed, while for making steel of greaterhardness---sueh, for instance, as is fit for tools for the turning ofchilled cast-iron rolls-as much as from thirty to forty parts of suchwhite specular crude metal to from sixty to seventy parts of suchmalleable iron may be sometimes used; but, if required for any purposewhere still greater hardness is desired or unobjectionable, as much asnearly fifty parts of such white specular crude metal to from fifty tosixty parts of malleable iron may sometimes be made use of withoutentirely or too far impairing or destroying its malleability or rendering it incapable of being forged or rolled; but these proportions maybe varied when using this or other sorts of crude and malle able iron,according to their own difference as to their quantities of containedcarbon, in order to produce a steel or steely iron in which the hardness(which is dependent mainly on its quantity of carbon) shall be such asin each case is required.

When the refined or finers metal is employed hum) A in carrying out myinvention, in substitution for the specular crude metals hereinbeforementioned, such refined or finers metal may be employed in the same ornearly the same proportions to the malleable iron as is herein beforedirected with respect to the specular white'crude metal. In carrying outmy said invention the above-described materials are to be melted intosteel or steely iron either in covered pots or crucibles of such size asare usually employed in making cast-steel by the common methods, andsuch pots or crucibles may be used in the ordinary cast-steel-meltingfurnaces, or my materials may be melted in large pots similar or nearlysimilar to such as are used by glass-makers, but of smaller size, andespecially of much lower height, in order to prevent their bursting bythe weight of metal, which larger pots, when such are used, may betapped at their bottoms, if that should be preferred to their removalfrom the furnace, as is usual in the case of smallerpots, or thematerials may be melted in an open hearth or chamber of the furnaceitself, and of course in that casein much larger masses than can well bedone in single pots embedded in the fuel in the ordinary furnaces, auditmay be conveniently drawn out by tapping from such hearth or chamberinto ladles or directly into ingot or other molds, or may be removedfrom a such furnaces by any other convenient means that may bepreferred, such mode of melting my materialsin such hearths orchambersof the furnace itself having great and special advantages, especially incases where the metal is required in large quantities or masses; butwhen my materials are thus melted in such hearths or chambers theyshould, as far as may be, be protected from casual or other contact withthe fuel, as it is entirely by contact therewith that it happens thatwhen melted in common refinery-furnaces, or in what are called founders.cupolas, both steel and malleable iron usually take up or retain somuch of carbon as to always alter the quality of the resulting metal,ifnot in every case to render it unmalleable. The materials shouldtherefore be melted in some one or other of the many sorts of air orblast reverberatin g furnaces in which, by doc precaution, the contactof the metal with the fuel or with some portion of it and with its dustor ashes, as also its contact with the uncombined oxygen, which may insuch cases be injuriously present in the gases of the furnace, may besufficiently if not totally prevented; and as I consider furnaces inwhich blast is used or air-furnaces in which there is a strong draft ofair are more difficult to be managed in these respects than isdesirable, I prefer and recommend the use of reverberating furnaces inwhich the draft of air into or through its grate and other openings maybe as small as is conveniently practicable, and that it is better todepend for the production of the high degree of heat required in theheating such furnaces in great part or altogether upon the combustion ofgasesa point which persons conversant with such operations and furnaceswould easilyattain to and effect by one or more of several simple andeasy constructions and contrivances-and with reference to these objectsI prefer and recommend the use of melting-furnaces in which the heat isso drawn from the gases constructed according to the plan or plans nowwell known as Siemens Patent Furnace or Furnaces, which I regard in theabove-mentioned respects as extremely suitable to be used for makingsteel by my invention, whether such steel is to be melted by the use ofpots placed in such furnaces, especially if used without covers, or in ahearth or chamber of such furnaces; but it will in general be foundadvisable when melting my materials in hearths or chambers of suchfurnaces or in uncovered pots which may be placed in them to cover thematerials with a thin or superficial coating of melted glass, which mayconsist of such broken glass as is obtained from ordinary sheet or crownglass or even from common black bottles, both of which are purchaseableat a low rate under the name of cullet, and either of which will befound both cheap and suitable. 1 further desire tointimate that thecrude metal and the malleable iron may be mixed in the first instanceeither cold or after being heated, or one or both of them, especiallythe crude metal, may be either entirely or nearly melted before beingmixed with the other material.

The steel or steely iron may be cast when melted into ingot molds orother molds of any size or form suitable for the uses which such metalis intended, or according as the produce may be intended to be forged orrolled or otherwise manipulated in any particular manner or foranyspecial object; and I desire it may be also noted that the additionof scrapsteel or steely iron of suitable or proper quality, whetherproduced by my process or ob tained from any other source or means, maybe made in larger or smaller quantities to my materials, not onlywithout any actual or material injury or disadvantage, but also to theeffect of facilitating the fusion thereof by form ing, as it were, abath for their more ready liquefaction.

Having now described and particularly ascertained the nature of my saidinvention and the manner in which the same is or may be used or carriedinto effect, I would observe, in conclusion,that what I consider to benovel and original, and therefore claim as the invention secured to meby the hereinbefore-in-parv recited Letters Patent, is

The production or manufacture of steel and iron of a steely quality,substantially as hereinbefore described and set forth.

In testimony whereof I have signed my name to this specification beforetwo subscribing witnesses.

Witnesses: CHAS. ATTWOODA WM. Enwn. RoBnvsoN, WILLIAM FENwIoK RAEBURN.

